Automatic transfer valve for pumps



INVENTOR ATTORNEY GUNN AUTOMATIC TRANSFER VALVE FOR PUMPS Filed April 3, 1951 Joseph B. 60/70 March 31, 1953 Patented Mar. 31, 1953 iu-NlT-Eo STATES PATENT OFFICE .AUTOMATIC'TRANSFER VALVE FOR PUMPS Joseph 'B. Gunn, North Hollywood, Calif fas- -:signor :to :Bendix Aviation Corporation, .South Bend, 1nd,, a corporation ..of Delaware Application April. 3, 1951, 'Serial1N0.219,054

13 Claims. (Cl. 137627) This invention "relates -to hydraulic systems in whichza load'norm'ally receives actuating fluid "from a primary pressure-source such as=a power driven pump or accumulator but must get fluid from an auxiliary source such as a'hand-pump in "the event of failure of theprimary source.

A general object'of theinvention'is to provide a pressure-actuated transfer valve for connecting alo'ad'to ajprimary pressure source while thelatter is functioning, and disconnecting the load from theprim'arysource and ,connectingit to an auxiliary source in responseto failure of the primary-source to deliver fluid at sufiicient pressure.

A more specific object is to provide a pressureactuated transfer valve that'is responsive to .a relatively low control pressure as compared .to the pressures in the transfer lines.

Another objectis to provide 'a transfer valve having relatively low leakage.

Other more specific objects andLfeatures of the invention will appear fromthe description to fol- 'low of "a particular embodimentof the invention. The single figure of the drawing shows in 1ongitudinal section a transfer valve in accordance with the invention, in a schematic diagram .of a hydraulic system in which the valve may be employed. Referring to the drawing, a valve l in accordance with the invention has a control port H a'primary inlet port 62, a secondary inlet port =13, and an outlet port M. The ports l2, l3 and M are duplicated at the opposite end of the valve and areidenti'fied'by the reference numerals 12a, 13a and Ma respectively.

Asillustrate'dgthe valve is employed in a hydraulic system including a reservoir l 5,-a'booster pump I,--:a main pump 11, a 4-way valve 8, an auxiliary hand pump l9, and a hydraulic motor 29. The purpose of the valve II] is to connect the motoreylinderfifl through thel-wayvalve I8 to the main pump 1 when the latter is functioning, and toconnect the motor to the hand pump ld-whenfthe pressure fluidsupply associated with thel-way valve 5-8 fails to function.

Ehe'loooster pump E16 draws fluid through a duct 22 from the reservoir 45 and delivers it through aduct 23 to :the mainpump ll, .whi'chin turn deliversit throughaduct .2 1 to then-way valve 1.8. The -4way valve :18 is of standard design having a=neutral {position in "which "the duct '24 is blocked (if thexvalve 1'815 of the 'closed center type) .or isconnected through a return duct 25 to ithereservoir "i5 lti'f thevalve l8 isof the open center typeli The valve It has two operated 'ductl l zto-aaduet '261lea'ding totheprimary inlet port 12, 'and connects a duct 2 'lea'dingto the primary inlet port l2'a tothe return duct25. In the other operated position "of -'valve I 8, it *connects the pump duct 24 to the ductZFandcOnnects the duct -2tto' the return duct 25.

In the illustrated embodiment, the "pressure of 'fiuid in the duct'z'flbetween the'booster l6-*an'd the main'pump 1'? is used to control the"valve I 0-, and for .this purpose the duct 23 is connected "by a duct 28 to the control pressureport l l. flswill appear from the description *of 'thevalve lll'to follow, when the booster pump lGfis functioning .and pressure is applied-from the duct 23 through the duct 28, to the control ,pressure .port 1| l,the primary inlet port 12 is connected ztoithe outlet port l4, which in turnis connected by a duct '29 to oneend of themotor'zll, and the port lZais connected .to .the output port Ma, which is -connected by a duct 30 to'the other end of themotor 28. .Hencethe motor .20 isresponsive to the main pressure fluid supply under the control of the valve I8.

Should'the booster pump-l Sbecome inoperative for any reason, control pressure will lno longer be applied to the port ll of the valve Ill and the latter will thereupon operate -to disconnect the ports .i Z-andl 2a-fr0m theportsM and Marespectively and will connect the sports 13 and 13a .to the ports .IA and Ma respectively, thereby connectingathe hand .pump 19 to .the motorl'll. The hand pump it may be of .thereversible type as shown, so that fluid can .beapplied .to either .end of thelmotor .20 and withdrawn from the other end depending upon the direction .of vrotation of the ,pump is.

Referring now .to valve TI 1!, .it comprises. ascasing consistingof'a. motor cylinder having end closure members -36 and 456a, which :may be secured tothe-cylinder 3.5 as .by-bolts 3-l. Flhemotor cylinder 35 contains a-pair of motor :pistons 38 :and 33a in opposite ends thereof. :Since the :opposite ends of the valve Ill are identical-in structure, only the elementsin theupper half \of the valve will be further described.

The motor pistonissisurged downwardly pyfa helical compression spring-"40 compressed between the'ipiston-tand the end closurem'ember 36 and2i's limited fin fits -.'d0WI1WaTd movement by a 'central annular ridge 4-! in the motor kcylinderflflhe upper "end :of the motor cylinder is vented to atmosphere'bya-venMZ. Theend closure member 35 defines a valve cylinder 'coaxial with the motor cylinder 35 and extendingtherfrom. upper-endportion of the cylinder 4-3 is'separatly formed as an insert-"44 topermitassemlbly of -the apparatus. This insert 44 is fitted into a counterbore 45 at the upper end of the closure member 36 and is held in place by a closure plug 46.

There is slidably mounted in the valve cylinder 43 a shuttle valve 41 having a poppet 48 integral therewith and positioned in an annular recess 49 in the valve cylinder 43 immediately below the insert 44. The shuttle valve 41 has two spaced lands 4' and 412 positioned below the poppet 48 and sealing with the cylinder 43, and a third land 413 sealing with that portion of the bore of the valve cylinder defined by the insert 44. The shuttle valve 41 has a central bore 50 extending therethrough, which bore is communicated by lateral bores 5|, above the poppet 48, with the annular recess 49, which recess is connected to the output port l4. The upper end of the shuttle valve 41 has a counterbore 53 containing a stationary piston 54 which is restrained against upward movement by contact with the end of the closure plug 45. A helical compression spring 55 compressed between a spring retainer 55, resting on the upper end of the shuttle valve 41, and the upper end of the closure plug 48 urges the shuttle valve into lower position in which the poppet 48 is seated against a seat 51 defined by the junction between the recess 48 and the portion of the valve cylinder 43 therebelow.

At its lower end, the shuttle valve 41 is provided with a counterbore 58 containing a piston 59, the inner end of which normally rests against the motor piston 38. This piston 59 has a tapered upper face constituting a poppet adapted to seat against the lower end of bore 58. The upper end of the counterbore 58 is communicatedwith an annular recess 68 which is defined by the two lands 4H and 412 and which is communicated by a passage 61 with the secondary inlet port [3.

The valve is shown in the position it assumes when there is no pressure in the control port II, and the piston 38 has been moved into its inner position by the spring 40, and the shuttle valve 41 has been moved into its inner position by the spring 55. Under this condition, it will be observed that flow inwardly through the inlet port I2 is blocked by the land 4' on' the shuttle valve and the poppet 4.8 thereon, which is seated against the seat 51. However, the secondary inlet port I3 is connected to the outlet port 14 through the passage 6|, the annular recess 68, the counterbore 58, the bore 50 (past the open poppet on piston 59), the passages and the recess 49. This is the position assumed in response to failure of pressure from the booster pump it, which failure results in the connection of the auxiliary pump IS in operative relation to the motor cylinder 28. The lower portion of the valve [8 functions in the same way to disconnect the outlet port [4a from the primary inlet port l2a and connect it to the other secondary inlet port l3a.

When pressure is supplied to the control port H, the motor piston 38 is moved upwardly against the force of the spring 48, carrying the piston 59 up until the poppet thereon closes against the lower end of the bore 58 in the shuttle valve, thereby cutting off communication between the secondary inlet port I 3 and the port l4. Final upward movement of the motor piston 38 and the piston 59 carries the shuttle valve 41 upward, lifting the poppet 48 oi the seat 51 and thereby communicating the primary inlet port 12 with the outlet port [4. Similar action in the lower half of the valve disconnects the output port l4a from the secondary inlet port l3a and connects it to the other primary inlet port lZc, so that the moor cylinder 20 is placed under the control of the 4-way valve I8, supplied with pressure fluid by the booster pump I8 and the main pump l1.

Where the main pressure fluid supply provides a low pressure and a high pressure, it is desirable to control the valve I0 from the low pressure rather than the high pressure, as is shown in the drawing. However, some problems are encountered in the control of fluid at high pressure by a fluid at low pressure. These problems have been solved in the valve In by providing the motor piston 38 of relatively large area compared to the area involved in the shuttle valve 41, and by balancing the shuttle valve with respect to the high pressure to which it is exposed. Thus when the shuttle valve is in inner position as shown, the pressure forces applied to the shuttle valve from the secondary inlet port [3 at the recess 68 are balanced, and the pressure forces applied to the shuttle valve at the ends of the counterbores 58 and 53 are balanced because these two counterbores are of the same diameter. The diameter of the seat 51 is the same as the diameter of the upper portion of the shuttle valve sealing with the insert 44, so that no unbalanced pressures are applied at that point. The upper end of the shuttle valve is exposed to atmospheric pressure, since the closure plug 48 is vented by a vent 10, and the inner end of the shuttle valve is vented to atmosphere through vent 42. All areas of the shuttle valve 48 exposed to high pressure fluid when the shuttle valve is in its outer position are also balanced by similar opposed areas. Of course, when the piston 59 is in its outer position sealing the lower end of the bore 58, an area of the piston equal to the area of the bore 58 is exposed to the high pressure in the ports !2 and i4 and this pressure must be overcome by the motor piston 38. It is for this reason that the motor piston 38 is made of much larger area than the port 58.

The valve is readily adaptable for use in a system in which the full output pressure of the main pump [1 is applied to the control port ll. However, under such conditions the motor cylinder 35 and the motor piston 38 can be made of much smaller diameter.

Although for the purpose of explaining the invention, a particular embodiment thereof has been shown and described, obvious modifications will occur to a person skilled in the art, and I do not desire to be limited to the exact details shown and described.

Iclaim:

1. A valve of the type described, comprising: a casing defining a motor cylinder and a coaxial valve cylinder extending outwardly from one end of said motor cylinder; a motor piston in said motor cylinder, said motor cylinder having a pressure-venting port on the outer side of said motor piston and having a control pressure port on the inner side of said motor piston, and spring means urging said piston inwardly in opposition to pressure in said control pressure port; said valve cylinder having an annular recess intermediate its ends defining an output chamber, and an output port in said casing communicating with said output chamber, the juncture of said annular recess and the portion of said valve cylinder on the inner side thereof defining a first poppet seat; said casing having a primary inlet port com municating with said valve cylinder on the inner side of said first seat and a secondary inlet port communicating with said valve cylinder at a point inwardly spaced from said primary port; a shuttle valve in said valve cylinder having a poppet portion intermediate its ends for seating against said first poppet seat, said shuttle valve havin a longitudinal bore therein; means sealing the outer end of said bore and a counterbore extending into said bore from the inner end thereof, the juncture of said bore and counterbore defining a second poppet seat, a port connecting said bore with said output chamber, and a port connecting said counterbore with said secondary inlet port; a piston valve in said counterbore and projecting inwardly therefrom for actuation by said motor piston, said piston valve having a poppet cooperating with said second poppet valve seat; and spring means urging said shuttle valve inwardly to seat said poppet portion of said shuttle valve against said first seat, said spring means yielding in response to predetermined pressure in said motor cylinder to permit said motor piston to first seat said piston valve against said second seat to break communication between said secondary inlet port and said output port and then unseat said poppet portion of said shuttle valve to communicate said primary inlet port with said outlet port.

2. A valve according to claim 1 having a second section identical with that described, extending from the inner end of the described section, the motor cylinder of each section being continuous with and constituting a closure member for the inner end of the other.

3. A valve according to claim 1 in which said shuttle valve has a second counterbore at the outer end thereof having the same diameter as the said counterbore of the inner end thereof; and said means for sealing the outer end of said bore comprising a piston in said second counter- .bore and means restraining outward movement of said last mentioned piston with respect to said casing;

JOSEPH B. GUNN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,206,957 Hose July 9, 1940 2,313,797 Bailey Mar. 16, 1943 2,563,419 Rockwell Aug. 7, 1951 

